gradient

In plane analytic geometry,
the gradient is an increase in y corresponding to a unit increase
in x. The gradient of a curve may
be found at any point along it by use of differential calculus.
Gradient is a vector quantity. In vector
notation, the gradient of a scalar field W is the vector field

grad W = i ∂W/∂x + j ∂W/∂y + k ∂W/∂z

In other words, the gradient is a vector of partial derivatives of a function that operates on vectors.